1. Field of the Invention
This invention relates generally to ore dressing methods and to concentration of metal values in ores by flotation. More particularly, the invention provides a new and valuable method of recovering metal values from ores, whereby flotation of a slurry of the ore is conducted in the presence of a frothing agent comprising a minor amount of a phosphorodithioic compound as synergistic adjuvant of frothing. This invention is distinct from that in co-pending application Ser. No. 622,473. The herein described invention relates to a novel application of phosphorodithio compounds as frother adjuvants in mixtures with other frothers. Co-pending application Ser. No. 622,473 employs phosphorodithio compounds as collectors in froth flotation. The distinction is that the present invention employs phosphorodithio compounds, not as collectors, but as adjuvants to frothing agents.
2. Description of the Prior Art
Flotation is a widely used method of concentrating ores. Froth flotation is a process for separating finely divided particles of valuable minerals from undesired materials with which they are associated. A pulp of the particles in water is mixed with a frothing agent and air is introduced into the mixture to give air bubbles. Particles of the minerals will become attached to the bubbles, whereas other minerals will not become so attached and remain in the pulp. As the froth is formed, it carries the mineral particles to the surface of the flotation system, and subsequent skimming results in recovery of the mineral.
The nature of the froth is often controlling in arriving at smooth and effective mineral recovery. A thin froth may not withstand separation. A copious froth may not provide selectivity. The froth structure should be strong enough to support not only fine particles, but also a heavier and coarser mineral load.
The flotation art has been well researched, and numerous materials have been found to serve as frothers: for example, aliphatic alcohols and ketones, terpenic compounds, and foam-producing surfactants such as the poly glycols and ethers. Industrially, frothers for use in ore flotation are of great importance, because even a very small improvement in the efficacy of the frothing agent can have immense commercial effect. With growing practice of tailing recycle, the cost efficiency of the frothing agent becomes increasingly significant.